1. Field of the Invention
The present invention relates to a contact structure having a compliant bump and a testing area and a manufacturing method for the same, and more particularly to a shift conductive compliant bump formed as an input/output contact on a silicon wafer.
2. Description of Related Art
To develop the field of manufacturing a high-density integrated circuit, an IC chip requires a highly-reliable physical and electrical structure. In order to manufacture a high-density IC structure, such as a high-resolution liquid crystal panel, in a tiny area, the control ICs used therein also need to be arranged densely. As such, conventional metal bumps formed as the conductive contacts used on the wafer were developed. The bump is either a gold bump, an eutectic solder bump, or a high lead solder bump, etc. Because the metal bumps used as the IC signal contacts are used upon smaller packaged products having a plurality of pins, the conventional technology of bonding or leading is not adopted.
U.S. Pat. No. 4,749,120 discloses a gold bump used as the conductive medium between the IC chip and the substrate. However, the process is the same as an assembling process combining the IC chip and the substrate and causes the chip to crack since a recovering force is generated in the duration of the process. Therefore, the prior art incorporates a conductive particle with elasticity or a relevant material of the like for preventing the above-mentioned crack.
U.S. Pat. No. 5,707,902 shown in FIG. 1 discloses a cross-sectional view of a bump structure formed on a circuit board. The major structure has a metal pad 16 formed on a substrate 1, and a passivation layer 18 having a protective function. The bump structure on the substrate 1 includes a polymer 12 and a conductive metal layer 14 coated thereon. In particular, the polymer 12 reduces the recovering force between the substrate and the circuit board.
A bump electrode for connecting electronic components disclosed in U.S. Pat. No. 5,477,087 is shown in FIG. 2. The cross-sectional view of the bump electrode on the circuit board shows a bump electrode 20 formed on a LSI chip 21, and an aluminum electrode 22 on the LSI chip 21. The electrode can be the conductive medium between the bumps and the circuit, and coated with insulation 23, furthermore, a barrier-metal layer 24 is formed between the etched insulations 23. The bump electrode 20 includes a resin 25, numerous cavities 26 thereon, and a conductive metal layer 27 coated thereon. The above-mentioned resin 25 in the bump electrode 20 and the cavities 26 are a compliant structure, which prevents damage occurring in the process of combining the chip with the bump electrode 20 or a circuit board and other components.
A further prior art is U.S. Pat. No. 5,508,228 which discloses the compliant electrically connective bumps for an adhesive flip chip integrated circuit device. FIG. 3 shows a three-dimensional view of the conductive bump, which is a portion of the IC 30. The plurality of conductive bumps 31 thereon is formed as the I/O contacts, and the conductive bumps 31 are prominent bumps. In particular, the top surface 34 and the adjacent side structure 36 connect to the bond pads 33 coupling to the IC 30 via the base 38, and the conductive bumps 31 connect to the wires 32 of the IC 30 via the bond pad 33. Polymer is used to manufacture the core of the above conductive bumps 31, so the bumps have compliant features.
The bump structures disclosed in the above-mentioned art are required to pass a variety of electrical examinations before being sold. The metal layer coated on the compliant bump structure can be broken when being probed by a probe since the metal layer is very thin. TW Patent No. 324847 discloses a complex bump structure used for an IC. FIG. 4 shows the input/output contacts of the IC, wherein the complex-type bump structure is formed on a substrate 40 having an input/output terminal pad 42 and a passivation layer 41 coated thereon. A first metal layer 43 is formed on the input/output terminal pad 42 and the passivation layer 41. Next, the patterned complex bump 44 is formed on the first metal layer 43 and on the input/output terminal pad 42 moved a shift distance away. After that, the first metal layer 43 and the complex bump 44 are formed as a second metal layer 45. The mentioned complex bump 44 forms an opening so as to electrically connect to the lower structure and other electric components, and the opening can be an area used for providing a good probing place.